Automatic sequencing high vacuum mechanical valve system and apparatus

ABSTRACT

A mechanical roughing vacuum pump and a high vacuum pump of the diffusion or similar type are interconnected to a high vacuum chamber and an intermediate isolation chamber. Valves are located within the chambers and are coupled with novel mechanical interlocks which provide for automatic operation of the valves by the pressure differential in the chambers and produce proper sequencing of the pumps to effect a high vacuum.

U Unite States Patent 1191 1111 3,829,244 Miller Au 13 1974 [5 AUTQMATMSEQUENCING HIGH 856,828 9/1957 Great Britain 417/152 VACUUM MECHANICALVALVE SYSTEM AND APPARATUS Primary ExaminerWilliam L. Freeh AssistantExaminer-Arnold Ward [76] Inventor' $2 2 gi 22 2 8 arbara Attorney,Agent, or Firm-Alfons Puishes [22] Filed: May 10, 1973 [57] ABSTRAQT[21] Appl' N05 359,207 A mechanical roughing vacuum pump and a highvacuum pump of the diffusion or similar type are inter- 52 us. or.417/53, 417/152 connected to a high vacuum chamber and an interme- [51]I t, Cl, F044 19/24, F04f 9/00 diate isolation chamber. Valves arelocated within the [58] Field at Search ..417/152 154, Chambers and areCoupled with novel mechanical n- 417 49 53 54 9 5 427; 55 20 339terlocks which provide for automatic operation of the valves by thepressure differential in the chambers and 5 References Cited produceproper sequencing of the pumps to effect a FOREIGN PATENTS ORAPPLICATIONS high vacuum.

904,684 3/1942 Germany 417/152 10 CIaims,7Drawing Figures W m r3 1Q 4454 m 4/ 1 I 45 4 504" g T 58 54 I ,!wm-r & "1- $\\:f\\5il\\\\v r ail /Is 1 s PATENIED w 1 W @9344 SHEU 1 [IF 2 PATENIED mm 1 31974 sum 2 0F 2AUTOMATIC SEQUENCING HIGH VACUUM MEQHANICAL VALVE SYSTEM AND APPARATUSBACKGROUND OF THE INVENTION In the production of vacuum conditionswherein the pressures achieved are Torr or lower, a combination of twoor more pumps is required. The relations of these pumps to each otherand the evacuated space during start-up, operation and shut-down need tobe controlled either manually or automatically in order to protect thepumps and the evacuated system against undesirable effects caused bymisoperation. Usually, when, the vacuum system operates for long periodsof time without shut-down, automatic start-up and shutdown controls arenot justifiable and perhaps only an alarm signal is included for powerfailure indication. In vacuum systems that must be brought back toatmospheric pressure several times a day, automatic sequencing controlsthat sense the pressures, amplify the minute electrical currents ofthese sensors and finally operate valves and perhaps other devices areemployed. In addition, automatic controls are sometimes a desirabletrade-off against training of personnel in high vacuum technique.

Frequently the much higher cost of the automatic sequencing controlsover the manual type can be offset by labor savings; but a much widernumber of cases could justify the automatic feature if its cost were tobe cut severely. Such reduction in cost I claim as one of the mainfeatures of my automatic sequencing mechanical valve system.

The particular combination of pumps mentioned above, namely a mechanicalpump and a diffusion pump is commonly used because the diffusion pumpcan produce pressures of 10 Torr and lower but cannot discharge directlyto the atmosphere. The mechanical pump of the common eccentric rotortype is not very effective at pressures below the 10 to 10" Torr rangebut can exhaust against atmospheric pressure. A simple seriesarrangement will function all right once the vacuum chamber is down to apressure of about 10* Torr. However, initial evacuation from atmosphericpressure and the return from high vacuum to atmospheric pressures arefacilitated by the addition of some valves and pumping lines as will bedescribed later.

The diffusion pump should be isolated from the rest of the system bysuitable valving arrangements. This will prevent overheating of thediffusion pumping fluid usually brought about by subjecting it to apressure higher than about 1 Torr. Also with proper valving thediffusing pumping fluid is prevented from backstreaming, an action thatwould result in fouling of the vacuum chamber. With the diffusion pumpthus isolated the vacuum chamber can be pumped down from atmosphericpressure to a pressure of 10 to 10 Torr. At this pressure the diffusionpump can be engaged by proper valve operation. Now the mechanical pumpbecomes a backing or fore pump to thediffusion pump.

Present practice employed to prevent misoperation uses pressure sensorsand power driven valves. Such systems, however, have several drawbacks:

1. They are complex and costly in that the pressure sensors areelectronic in nature with thermocouple or similar hot-filament gaugeshaving low-level electrical output signal which must be amplified tocontrol electric motors or pneumatic or hydraulic valves which, in turn,are arranged to operate the vacuum valves by means of screws, linkagesor pistons. 2. They are ordinarily bulky and heavy because of the manydiscrete components used in the system. 3. They are inherentlyunreliable in that auxiliary power sources are required for the controlfunctions which sources are in themselves subject to failure. Thusadditional devices of a safety nature are necessary which will shut downthe system or otherwise compensate for any of the various possiblefailures.

SUMMARY OF THE INVENTION.

My invention described below eliminates the disadvantages ofcontemporary vacuum pumping systems in that the vacuum valves areself-operating in a sequential manner using the differential pressuresacross each valve poppet. A single mechanical rod or shaft, hereinafterknown as the operating shaft, is used to initiate the desired operatingsequence or to return the system to atmospheric pressure when desired.

My invention, described more fully below in relation to the prior artconsists of three valves which are functionally identical to the priorart valves, but physically arranged so that a roughing valve and a highvacuum valve are mounted in the high vacuum chamber, and an isolationvalve is mounted in a separate, sealed chamber designated as theisolation valve chamber. An operating shaft connects between theisolation valve chamber and the vacuum chamber and carries theappropriate linkages by which all three valves are controlled.

Vacuum connections to the isolation valve chamber are so arranged thatthe outlet from the roughing valve and the inlet to the mechanical pumpare both connected to the space surrounding the isolation valve, whilethe outlet from the diffusion pump is connected to the space below theisolation valve poppet. The isolation valve may consist of a relativelylarge area poppet suspended by a pivoted arm arrangement having anintegral counterweight which is adjusted so that the valve is biased bythe counterweight to the open position, also as described more fullybelow.

I have discovered that when utilizing the novel construction of myapparatus and the construction and location of my valves I am able toeffect a completely automatic sequencing of the valves to operate a highvacuum system. I am further able to accomplish this without the use ofcomplex electrical circuitry or controls. The latter feature eliminatesthe hazards attendant upon complete power failure.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating abasic vacuum pump combination in its simplest form.

FIG. 2 is a schematic diagram illustrating a vacuum pump combinationillustrating the use of an isolation valve.

FIG. 3 is a schematic diagram illustrating the combination of myinvention.

FIG. 4 is a longitudinal section through the isolation chamber of myinvention showing the isolation valve and related mechanism andconnections.

FIG. 5 is a longitudinal section through the isolation chamber and highvacuum chamber showing the operating valves and mechanism at thestarting stage of evacuation.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the figures andfirst to FIG. I there is shown diagrammatically conventional connectionsfor producing a high vacuum. These comprise the vacuum chamber 1 with avacuum breaker valve 2 used in all the systems but shown only in thisFIG. The diffusion pump 3 connects to the vacuum chamber and thence topipeline 4 to the inlet to a mechanical vacuum pump or what is known inthe art as a roughing pump which exhausts to the atmosphere at 6. Such aconnection presents all the problems and hazardous disadvantagesenumerated under the background of the invention described above.

Referring now to FIG. 2 there is seen the vacuum chamber 21, a highvacuum valve 22 connecting to the diffusion pump 23. Twenty-four, 24a,and 24b represent lines leading from the discharge of the diffusion pump23 and from the vacuum chamber 21 to the mechanical pump 25, havingitsexhaust at 26. A pressure sensor 27 is employed to operate roughingvalve 28 and isolation valve 29 whereby through suitable electrical orelectronic means the roughing pump 25 is first connected to vacuumchamber 21 until the vacuum reaches a predetermined point, whereuponvalve 28 is closed and valve 29 opens, or is opened, thereby producingthe connections shown in FIG. 1. Such a system overcomes many of theobjections as described above but necessitates the use of highlysensitive sensing equipment represented at 27 with their attendantcontrols and consequently results in a highly expensive, complicated andtroublesome arrangement.

Referring now to FIGS. 3 and 4 there is seen first in FIG. 3 a schematicdiagram of the connections forming the basis of my invention and in FIG.4 the mechanical components comprising and located in the isolationvalve chamber which forms'an important part of my invention.

Inside vacuum chamber 31 is located high vacuum valve 32 which connectsto diffusion pump 33 and thence through pipeline 34 to isolation chamber40 through isolation valve 39 which is located inside the chamber asexplained more fully below. Roughing valve 38 is located inside highvacuum chamber 31, and connects to isolation chamber 40. Operating shaft41 with its handle 42 passes through seals 43 in isolation valve chamber40 and serves for positioning of the valves as described more fullybelow.

Operating shaft 41 and seals 43 located in isolation valve chamber 40are better seen on FIG. 4. This is seen connected through linkage 44 andpush rod and roller 45 to the mechanism of isolation valve 50. A levercomprising a pivot 47 and counterweight 48 is shown bearing upon the topof the poppet 50a of isolation valve 50. This combination permitsbiasing the valve to an open position when no pressure differentialexists across the poppet 50a. The outlet from the roughing valve isshown at 51, the outlet from the diffusion pump at 52, and the inlet tothe mechanical pump at 53, all communicating to the interior ofisolation valve chamber 40 as shown.

On FIG. is seen isolation valve chamber 40 shown in juxtaposition withhigh vacuum chamber 54. Inside the latter is shown roughing valve 55havings its valve seat 55a and its flexible tube 55b leading to theisolation chamber 40 at 51. High vacuum valve 56 with its poppet 56a isseen located inside high vacuum chamber 54. A lever mechanism comprisinga pivot 57 and adiO justable counterweight 58 is shown bearing on theupper side of poppet 56a in a manner similar to that described above forthe isolation valve. The inlet to the diffusion pump is seen at 59.

Operating shaft 41 described above is seen passing through high vacuumchamber 54 and having positioned upon it spring 60, collars 61 andlinkage 62. Also operating shaft 41 extends (not shown) to a vacuumbreaker valve (not shown) to open and close it as described more fullybelow. The operating shaft is equivalent to a start and stop button. Itis manually controlled. In the position shown in FIG. 5 the vacuumchamber 54 is at atmospheric pressure, the vacuum breaker valve is openand the mechanical pump is pumping on the outlet of the diffusion pumpthrough isolation valve 50. To initiate evacuation of the vacuumchamber, operating shaft 41 is moved to the left resulting in theposition shown in FIG. 6. This closes isolation valve 50, opens roughingvalve 55 and closes vacuum breaker valve (not shown). Now conditionshave been established to permit automatic sequence operation ofisolation valve 50 and high vacuum valve 56. As the pressure inisolation chamber 40 is reduced by action of the mechanical pump,isolation valve 50 opens. Similarly, and in sequence, as the pressure inthe vacuum chamber 54 decreases, high vacuum valve 56 opens. In so doingit back seats against and, consequently, closes the roughing valve sothat the pumping flow is as shown in FIG. 7.

OPERATION The operating shaft is operated so that the isolation valve 50is forced closed for a portion of the travel of the operating shaft andlinkage. Thus, as the operating shaft 41 moves, the isolation valve 50is forced to its closed position, and then released at the other extremeposition of the operating shaft as best seen on FIG. 6.

While I have shown a sliding shaft, I may use also a rotating shaft withappropriate connecting linkages as is well known to those skilled in theart.

As shown also on FIG. 6, the high vacuum valve is mounted in the vacuumchamber and is similar in construction and operation to the isolationvalve ad described above, with the space under the high vacuum valveconnected to the inlet of the diffusion pump. The separate roughingvalve 55 is mounted from the same pivot shaft so that it seals againstthe upper surface of the high vacuum poppet 56a, but does not interferewith the action of the high vacuum valve 56 counterweight when theroughing valve is in the open position.

ber. The spring-loaded linkage 62 connecting the operating shaft to theroughing valve maintains the roughing valve sealed against the highvacuum valve during the condition when the vacuum chamber is atatmospheric pressure. To initiate operation the operating shaft ismanually pulled to the left which engages the linkage to the roughingvalve 55 and lifts the roughing valve off the surface of the high vacuumvalve, commencing evacuation (or roughing) of the vacuum chamber 54. Atthe same time the operating shaft closes the isolation valve 50 and alsocloses the vacuum breaker valve. At the initial opening of the roughingvalve, the pressure in the isolation valve chamber increases momentarilyas air flows in from the vacuum chamber which was at atmosphericpressure. This maintains the isolation valve sealed closed while the airis being evacuated from the vacuum chamber as shown in FIG. 6. It shouldbe noted that the isolation valve chamber is now connected to the vacuumchamber through flexible tube 55b and roughing valve 55. Therefore asroughing continues the pressure in the two chambers will becomeessentially equal, except for the slight differential due to the airflow.

When the pressure in both chambers declines to a predetermined value asdetermined by the setting of the isolation valve counterbalance weight48, the pressure differential across the isolation valve poppet will nolonger be sufficient to hold the isolation valve closed against thecounterbalance force, thus the isolation valve will open. In practice,the isolation valve counterweight is adjusted so that the valve opens ata pressure of approximately 0.5 Torr.

With the isolation valve opened, the diffusion pump outlet is againconnected to the roughing pump. As the pressure continues to decline toa second predetermined point in the vacuum chamber, the high vacuumvalve is caused to open by its counterweight as shown in FIG. 7. Thissecond pressure is characteristically set at 0.1 Torr. The physicalarrangement of the roughing valve and the high vacuum valve is such thatin its open position, the high vacuum valve rests against and seals theinlet of the roughing valve; thus with the high vacuum valve opened, thevacuum chamber is connected to the inlet of the diffusion pump andeffectively sealed from the roughing pump by the high vacuum valvepoppet. In this condition then, it can be seen that the vacuum chamberis connected through the diffusion pump to the mechanical pump in thedesired configuration shown diagrammatically in FIG. 1.

When it is desired to vent the vacuum chamber to atmosphere, theoperating shaft is once again caused to move to the condition shown inFIG. 5 and the vacuum chamber is vented to atmosphere by means of avacuum breaker valve, (not shown).

It must be recognized that the particular mechanical arrangement ofvalves and operating linkages described above is only one of the manypossible configurations of this invention, any of which may embody itsunique characteristics, namely, the combination of two or more valves,some of which are directly mechanically operated and otherscounterbalanced by springs or weights, so arranged that actuation of themechanically operated valves will establish the required mechanicalconditions so that the counterbalanced valves will operate in somedesired sequence, depending only upon the pressure differentials acrossthe counterbalanced valves and the pressures in the chambers.

The novel construction of my apparatus and the location of the valvesmakes possible: their sequential operation by extremely small pressuredifferentials which exist in vacuum operations.

While I have disclosed a combination of a mechanical pump and adiffusion pump for use in connection with my invention, it will beevident to those skilled in the art that other suitable types ofconventional and high vacuum pumps may be used in combination to effeetthe novel results attained by my invention.

I claim:

1. An apparatus for effecting the evacuation of a chamber to a highvacuum by use of a mechanical pump together with a diffusion pumpcomprising the combination of:

an intermediate vacuum chamber communicating between said high vacuumchamber and the inlet to said mechanical pump;

a first valve positioned inside said intermediate chamber andcommunicating between the outlet from said diffusion pump and saidintermediate chamber; said first valve being disposed to open and closeautomatically when the pressure differential across said valve reachespredetermined values;

a second valve positioned inside said high vacuum chamber andcommunicating between the inlet to said diffusion pump and said highvacuum chamber; I said second valve being disposed to open and closeautomatically when the pressure differential across said valve reachespredetermined values;

a third valve positioned inside said high vacuum chamber communicatingbetween said high vacuum chamber and said intermediate chamber; saidthird valve being disposed to close automati cally when said secondvalve opens; independent means for simultaneously closing said firstvalve and opening said third valve.

2. The apparatus of claim 1 including means for applying a variablemechanical force to one side of said first valve and said second valvewhereby said pressure differential required to open and close said valvemay be varied.

3. The apparatus of claim 1 in which said independent means comprises:

a shaft mounted axially through said intermediate chamber and said highvacuum chamber;

a first linkage mechanism engaging said shaft within said intermediatechamber; said first mechanism being operably engaged with said firstvalve;

a second linkage mechanism engaging said shaft within said high vacuumchamber; said second mechanism being operably engaged with said thirdvalve;

whereby movement of said shaft closes said first valve and opens saidthird valve simultaneously.

4. The apparatus of claim 1 including a first pivoted lever and a secondpivoted lever;

one end of said first lever being disposed for contact with said firstvalve and one end of said second lever being disposed for contact withsaid second valve;

counterweights positioned on the opposite ends of each of said levers;

means for varying the position of said counterweights on said levers;whereby said pressure differential required to open and close saidvalves may be varied.

5. In an apparatus for effecting the evacuation of a chamber to a highvacuum by use of a mechanical pump together with a diffusion pump thecombination of:

a first valve communicating between said high vacuum chamber and theinlet to said diffusion pump;

a second valve communicating between said high vacuum chamber and theinlet to said mechanical P p said first valve being disposed to open andclose automatically when the pressure differential across said valvereaches predetermined values;

said second valve being positioned in cooperative relation to said firstvalve whereby said second valve is opened automatically when said firstvalve closes and is closed automatically when said first valve opens. I

6. The apparatus of claim in which said second valve is positionedadjacent to said first valve;

said valves being disposed for axial movement with relation to eachother;

a seating surface positioned on a face of said second valve;

a seating surface positioned on a face of said first valve;

said surfaces being disposed for engagement with each other;

whereby opening and closing of said second valve may be effected by saidrelative movement of said valves.

7. In an apparatus for effecting the evacuation of a chamber to a highvacuum by use of a mechanical pump together with a diffusion pump theimproved combination comprising:

a separate isolation valve chamber connecting to said high vacuumchamber and communicating with the outlet from said diffusion pump andthe inlet to said mechanical pump;

a balanced isolation valve positioned within said chamber andcommunicating with said outlet of 8 said diffusion pump;

adjustable balancing means positioned upon one side of said valve withinsaid chamber;

said balancing means being disposed to cause said valve to open andclose at relatively low pressure differentials across said valve whilesaid chamber is under a vacuum;

whereby sequential operation of said pumps on said high vacuum chambermay be effected.

8. A method of operating an automatic high vacuum mechanical valvesystem utilizing interconnected mechanical and diffusion pumpscommunicating with interconnected vacuum chambers and comprisingbalanced valves positioned within said chambers comprising the steps:

manually closing a first of said balanced valves positioned in a firstof said vacuum chambers and communicating with the outlet of a diffusionpump and;

simultaneously closing a second of said balanced valves positioned in asecond vacuum chamber and communicating with the inlet of said diffusionpump and;

simultaneously opening a third valve positioned in the interconnectionbetween said first chamber and said second chamber and communicatingwith the inlet of a mechanical pump; operating said mechanical pumpthereby reducing the pressures in said chambers and producing pressuredifferentials across said balanced valves;

continuing said operating until said pressure differentials and thepressures in said'chambers reach predetermined values thereby causingsaid balanced valves to open sequentially;

simultaneously closing said third valve as said second valve opens.

9. The method of claim 8 in which said first valve is caused to openwhen the pressure in said first chamber reaches approximately 0.5 Torr.

10. The method of claim 9 in which said second valve is caused to openwhen the pressure in said second chamber reaches approximately 0.1 Torr.

1. An apparatus for effecting the evacuation of a chamber to a highvacuum by use of a mechanical pump together with a diffusion pumpcomprising the combination of: an intermediate vacuum chambercommunicating between said high vacuum chamber and the inlet to saidmechanical pump; a first valve positioned inside said intermediatechamber and communicating between the outlet from said diffusion pumpand said intermediate chamber; said first valve being disposed to openand close automatically when the pressure differential across said valvereaches predetermined values; a second valve positioned inside said highvacuum chamber and communicating between the inlet to said diffusionpump and said high vacuum chamber; said second valve being disposed toopen and close automatically when the pressure differential across saidvalve reaches predetermined values; a third valve positioned inside saidhigh vacuum chamber communicating between said high vacuum chamber andsaid intermediate chamber; said third valve being disposed to closeautomatically when said second valve opens; independent means forsimultaneously closing said first valve and opening said third valve. 2.The apparatus of claim 1 including means for applying a variablemechanical force to one side of said first valve and said second valvewhereby said pressure differential required to open and close said valvemay be varied.
 3. The apparatus of claim 1 in which said independentmeans comprises: a shaft mounted axially through said intermediatechamber and said high vacuum chamber; a first linkage mechanism engagingsaid shaft within said intermediate chamber; said first mechanism beingoperably engaged with said first valve; a second linkage mechanismengaging said shaft within said high vacuum chamber; said secondmechanism being operably engaged with said third valve; whereby movementof said shaft closes said first valve and opens said third valvesimultaneously.
 4. The appaRatus of claim 1 including a first pivotedlever and a second pivoted lever; one end of said first lever beingdisposed for contact with said first valve and one end of said secondlever being disposed for contact with said second valve; counterweightspositioned on the opposite ends of each of said levers; means forvarying the position of said counterweights on said levers; whereby saidpressure differential required to open and close said valves may bevaried.
 5. In an apparatus for effecting the evacuation of a chamber toa high vacuum by use of a mechanical pump together with a diffusion pumpthe combination of: a first valve communicating between said high vacuumchamber and the inlet to said diffusion pump; a second valvecommunicating between said high vacuum chamber and the inlet to saidmechanical pump; said first valve being disposed to open and closeautomatically when the pressure differential across said valve reachespredetermined values; said second valve being positioned in cooperativerelation to said first valve whereby said second valve is openedautomatically when said first valve closes and is closed automaticallywhen said first valve opens.
 6. The apparatus of claim 5 in which saidsecond valve is positioned adjacent to said first valve; said valvesbeing disposed for axial movement with relation to each other; a seatingsurface positioned on a face of said second valve; a seating surfacepositioned on a face of said first valve; said surfaces being disposedfor engagement with each other; whereby opening and closing of saidsecond valve may be effected by said relative movement of said valves.7. In an apparatus for effecting the evacuation of a chamber to a highvacuum by use of a mechanical pump together with a diffusion pump theimproved combination comprising: a separate isolation valve chamberconnecting to said high vacuum chamber and communicating with the outletfrom said diffusion pump and the inlet to said mechanical pump; abalanced isolation valve positioned within said chamber andcommunicating with said outlet of said diffusion pump; adjustablebalancing means positioned upon one side of said valve within saidchamber; said balancing means being disposed to cause said valve to openand close at relatively low pressure differentials across said valvewhile said chamber is under a vacuum; whereby sequential operation ofsaid pumps on said high vacuum chamber may be effected.
 8. A method ofoperating an automatic high vacuum mechanical valve system utilizinginterconnected mechanical and diffusion pumps communicating withinterconnected vacuum chambers and comprising balanced valves positionedwithin said chambers comprising the steps: manually closing a first ofsaid balanced valves positioned in a first of said vacuum chambers andcommunicating with the outlet of a diffusion pump and; simultaneouslyclosing a second of said balanced valves positioned in a second vacuumchamber and communicating with the inlet of said diffusion pump and;simultaneously opening a third valve positioned in the interconnectionbetween said first chamber and said second chamber and communicatingwith the inlet of a mechanical pump; operating said mechanical pumpthereby reducing the pressures in said chambers and producing pressuredifferentials across said balanced valves; continuing said operatinguntil said pressure differentials and the pressures in said chambersreach predetermined values thereby causing said balanced valves to opensequentially; simultaneously closing said third valve as said secondvalve opens.
 9. The method of claim 8 in which said first valve iscaused to open when the pressure in said first chamber reachesapproximately 0.5 Torr.
 10. The method of claim 9 in which said secondvalve is caused to open when the pressure in said second chamber reachesapproximately 0.1 Torr.